This invention relates to alpha-olefin polymerization catalysts and particularly relates to catalyst systems which are highly active.
The polymerization of alpha-olefins to normally solid, substantially crystalline polymers using hydrocarbon soluble catalysts comprising transition metal compounds and Group II-III metal organic compounds now is well-known in the art. Supporting such transition metal compounds on a Group II metal hydroxide also is known. For example, British Pat. Nos. 1,208,242 and 1,255,575, and U.S. Pat. No. 3,900,454, all incorporated by reference herein, disclose an olefin polymerization catalyst formed by calcining a trivalent metal halide, such as aluminum chloride, with a Group IIA, IIB, and VIIB hydrous oxide, such as magnesium hydroxide, followed by the addition of a Group IVB or VB hydroxide or alkoxide, transition metal halide, such as titanium tetrachloride. However, there is a continuing need in the industry for improved catalyst systems which produce a high yield of polymer as measured by the grams of crystalline product per gram of transition metal compound consumed.